What does HRESULT 0x80010129 (CO_E_FAILEDTOSETDACL) mean?

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CO_E_FAILEDTOQUERYCLIENTBLANKET	CO_E_ACCESSCHECKFAILED

CO_E_FAILEDTOSETDACL

COM could not place a DACL in the security descriptor

CO_E_FAILEDTOSETDACL is HRESULT 2147549481 (0x80010129) from winerror.h. AllStat describes it as “Unable to set a discretionary ACL into a security descriptor.” In the COM IAccessControl, DCOM client identity, trustee translation, token inspection, security descriptor, ACL, or serialization workflow, the code identifies a specific failure boundary and should not be replaced by a generic COM exception.

Handling CO_E_FAILEDTOSETDACL correctly requires the code-specific postcondition, not merely the fact that FAILED(hr) is true.

Decisive interpretation boundary

Before choosing recovery, verify that the ACL is structurally valid, self-relative versus absolute form is correct, and owner/group fields satisfy the consuming API. That boundary prevents CO_E_FAILEDTOSETDACL from being misclassified as corruption, network failure, or a reason for an unsafe automatic retry.

For CO_E_FAILEDTOSETDACL, also confirm that all observed objects, tokens, buffers, proxies, metadata files, or ACLs belong to the current operation generation and were not retained from an earlier attempt.

Where it is encountered

• CO_E_FAILEDTOSETDACL can be returned during IAccessControl initialization, access checks, owner/trustee processing, and serialized ACL persistence. For CO_E_FAILEDTOSETDACL, record the interface, method, component version, thread, apartment, process, and correlation ID.
• CO_E_FAILEDTOSETDACL can be returned during server-side DCOM impersonation, client blanket inspection, token and SID lookup. For CO_E_FAILEDTOSETDACL, record the interface, method, component version, thread, apartment, process, and correlation ID.
• CO_E_FAILEDTOSETDACL can be returned during security descriptor construction, DACL canonicalization, file-backed policy storage, or legacy NetAccess migration. For CO_E_FAILEDTOSETDACL, record the interface, method, component version, thread, apartment, process, and correlation ID.

The immediate focus for CO_E_FAILEDTOSETDACL is construction or update of a COM access-control security descriptor where the discretionary ACL cannot be attached or validated. Keep CO_E_FAILEDTOSETDACL attached to that operation; the same numeric severity outside the owning API does not supply enough context.

Diagnostic sequence

• Capture the raw unsigned value 0x80010129 and symbolic name CO_E_FAILEDTOSETDACL before a language projection, exception wrapper, or generic COM helper replaces it.
• Identify the exact interface, method, callback, activation request, metadata query, access-control operation, or marshaling boundary that returned CO_E_FAILEDTOSETDACL.
• Reconstruct the operation timeline for CO_E_FAILEDTOSETDACL, including object creation, thread or apartment initialization, security setup, callbacks, mutations, shutdown, and cleanup.
• Prove the decisive condition: the ACL is structurally valid, self-relative versus absolute form is correct, and owner/group fields satisfy the consuming API.
• Inspect every output parameter, handle, interface pointer, token, SID, ACL, stream, buffer, server-side object, or asynchronous result produced before CO_E_FAILEDTOSETDACL.
• Reproduce CO_E_FAILEDTOSETDACL with the smallest safe input, change only the suspected precondition, and verify that both the HRESULT and postcondition change as predicted.

Evidence and telemetry

• Preserve security descriptor control flags for CO_E_FAILEDTOSETDACL.
• Preserve absolute or self-relative format for CO_E_FAILEDTOSETDACL.
• Preserve ACL size and ACE count for CO_E_FAILEDTOSETDACL.
• Preserve SID validation results for CO_E_FAILEDTOSETDACL.
• Preserve SetSecurityDescriptorDacl error for CO_E_FAILEDTOSETDACL.

For CO_E_FAILEDTOSETDACL, also record UTC time, process and thread IDs, apartment type, component version, security or package identity where relevant, and a correlation ID. For CO_E_FAILEDTOSETDACL, use hashes, lengths, GUIDs, and SID strings rather than logging confidential payloads or credentials.

Correct handling and recovery

Rebuild the descriptor with documented security APIs, validate every ACE and SID, and apply the DACL only after canonical ordering.

For CO_E_FAILEDTOSETDACL, reconcile partial output and server-side effects before attempting the operation again.

Difference from nearby HRESULTs

CO_E_FAILEDTOSETDACL is descriptor assembly failure; CO_E_ACCESSCHECKFAILED occurs when evaluating an assembled descriptor.

Merging CO_E_FAILEDTOSETDACL with the neighboring HRESULT would choose the wrong retry, recreation, authorization, or cleanup path.

Lifetime, retry, and cleanup rules

After CO_E_FAILEDTOSETDACL, determine whether the current object, interface pointer, call context, token, stream, metadata reader, asynchronous operation, or access-control instance remains valid. For CO_E_FAILEDTOSETDACL, release only resources owned by the failing attempt, cancel callbacks through their documented mechanism, and avoid double close, double commit, repeated activation, or replay of a non-idempotent remote method.

The retry policy for CO_E_FAILEDTOSETDACL should state the trigger, maximum attempts, cancellation owner, and reconciliation step for effects that may have completed elsewhere.

Developer and administrator guidance

When CO_E_FAILEDTOSETDACL crosses native, managed, scripting, RPC, or WinRT projection boundaries, preserve the unsigned 32-bit HRESULT. Unit tests for CO_E_FAILEDTOSETDACL should assert the code-specific postcondition and resource ownership, not merely that an exception was thrown.

For CO_E_FAILEDTOSETDACL, change the smallest component, identity, ACL, package, or threading boundary that the evidence identifies, then reproduce the same operation. Define who owns retry, cancellation, cleanup, policy changes, package repair, and user-facing messaging for CO_E_FAILEDTOSETDACL.

Practical scenario

A configuration tool builds a self-relative descriptor but calls a setter that expects absolute pointers. It converts format explicitly and verifies the resulting DACL.

A regression test should reproduce CO_E_FAILEDTOSETDACL, assert the raw HRESULT and all relevant outputs, then correct only the decisive condition and verify the intended success or neighboring failure result.

References

• Microsoft: IAccessControl — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: IAccessControl::IsAccessAllowed — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: AccessCheck — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: LookupAccountSidW — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: LookupAccountNameW — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: access control lists — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: canonical ACE order — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.
• Microsoft: HRESULT values — official Microsoft documentation relevant to CO_E_FAILEDTOSETDACL.

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